COAS Physics2 Teacher ResourcesOriginal material © Cambridge University Press 20091
1 Marking scheme: End-of-chapter test
1A reaction in which a nucleus (e.g. of ) absorbs a neutron and then splits intotwo
smaller nuclei (and some extra neutrons).[1]
The fission reaction will not occur without the neutron.[1]
2aThe energy of an electron moving is greater because it has kinetic energy.[1]
According to Einstein’s equation: ΔE = Δmc2[1]
An increase in energy implies greater mass.[1]
Hence, the mass of the moving electron is greater than its ‘rest’ mass.
biEk = mv2 = × 9.1 × 1031 × (2.0 × 107)2[1]
Ek = 1.82 × 1016 J 1.8 × 1016 J[1]
iiΔm = [1]
Δm = 2.02 × 1033 kg 2.0 × 1033 kg[1]
3aIt is a proton.[1]
bAny two from:[2]
•charge (or proton number)
•nucleon number
•mass–energy
•momentum.
4
mass defect Δm= [(3 × 1.009) + (3 × 1.007)]u – (6.014)u[1]
Δm= 0.034 u = 0.034 × 1.66 × 1027 kg[1]
Δm= 5.644 × 1029 kg[1]
binding energy = Δmc2[1]
binding energy = 5.644 × 1029 × (3.0 × 108)2 = 5.080 × 1012 J[1]
binding energy per nucleon =
binding energy per nucleon = = 8.466 × 1013 J 8.5 × 1013J[2]
5aThe positive nuclei repel each other.[1]
At higher temperatures the nuclei move faster[1]
and have a greater chance of approaching close enough so that they combine with each
other due to the strong nuclear force.[1]
biA neutron contains only one nucleon(), so it has no binding energy.[1]
iiEnergy released = difference in binding energy[1]
energy released = (11.2 × 1013 × 4) – [(1.0 × 1013 × 2) + (2.9 × 1013 × 3)][1]
energy released = 3.41 × 1012 J 3.4 × 1012 J[1]
COAS Physics2 Teacher ResourcesOriginal material © Cambridge University Press 20091